U.S. Pat. No. 6,250,759 describes spectacle lenses suitable for the practice of leisure activities, such as golf, hunting or fishing. Such lenses are divided into several zones whose characteristics of light transmission are adapted according to the objects or the landscape viewed during the practice of these activities. In particular, distinct zones of the lens may have different characteristics of filtering the light according to a polarization of the latter.
Natural light is not polarized; the electromagnetic waves of which it consists vibrate in all directions. David Brewster (from 1811) showed that, for a certain incidence, a monochromatic light reflected onto a transparent surface is polarized 100%. Brewster's Law stipulates that the direction of polarization of the reflected wave is parallel to the plane of reflection. This is why the reverberation of light on a horizontal plane will be polarized horizontally. Polarizing ophthalmic lenses were designed in response to these physical properties of reflected light. A lens whose direction of polarization is horizontal selectively filters the light rays originating from the reflection on horizontal transparent surfaces. These lenses are particularly effective for eliminating the annoying reverberations on surfaces of water, on ground coverings, on sand or snow. Nevertheless, the horizontal reflecting surfaces do not form the majority of the potential sources of dazzling. This is why the light reflecting on the panes of a building or a motor vehicle will, in the converse to the case previously described, be polarized vertically. The polarizing lenses currently available on the market are therefore totally ineffective for protecting the observer against these light attacks.
Certain features of the landscape present in the field of vision of a person are particular to the urban environment. The urban environment in particular has many vertical reflecting surfaces, such as, for example, building windows. These vertical walls generate reflections whose intensity can be sufficient to cause dazzling. Such dazzling is a source of discomfort, but it may also be a source of danger in certain circumstances. This is the case for a motor vehicle or motorcycle driver, for example.